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author:("branton, John")
1.  Utility of the Physical Examination in Detecting Pulmonary Hypertension. A Mixed Methods Study 
PLoS ONE  2014;9(10):e108499.
Patients with pulmonary hypertension (PH) often present with a variety of physical findings reflecting a volume or pressure overloaded right ventricle (RV). However, there is no consensus regarding the diagnostic utility of the physical examination in PH.
We conducted a systematic review of publications that evaluated the clinical examination and diagnosis of PH using MEDLINE (1946–2013) and EMBASE (1947–2013). We also prospectively evaluated the diagnostic utility of the physical examination findings. Patients who underwent right cardiac catheterization for any reason were recruited. After informed consent, participants were examined by 6 physicians (3 “specialists” and 3 “generalists”) who were unaware of the results of the patient's hemodynamics. Each examiner independently assessed patients for the presence of a RV lift, loud P2, jugular venous distension (JVD), tricuspid insufficiency murmur and right-sided 4th heart sound at rest and during a slow inspiration. A global rating (scale of 1–5) of the likelihood that the patient had pulmonary hypertension was provided by each examiner.
31 articles that assessed the physical examination in PH were included in the final analysis. There was heterogeneity amongst the studies and many did not include control data. The sign most associated with PH in the literature was a loud pulmonic component of the second heart sound (P2). In our prospective study physical examination was performed on 52 subjects (25 met criteria for PH; mPAP ≥25 mmHg). The physical sign with the highest likelihood ratio (LR) was a loud P2 on inspiration with a LR +ve 1.9, 95% CrI [1.2, 3.1] when data from all examiners was analyzed together. Results from the specialist examiners had higher diagnostic utility; a loud P2 on inspiration was associated with a positive LR of 3.2, 95% CrI [1.5, 6.2] and a right sided S4 on inspiration had a LR +ve 4.7, 95% CI [1.0, 15.6]. No aspect of the physical exam, could consistently rule out PH (negative LRs 0.7–1.3).
The presence of a loud P2 or audible right-sided 4th heart sound are associated with PH. However the physical examination is unreliable for determining the presence of PH.
PMCID: PMC4208756  PMID: 25343585
2.  Critical care trainees’ career goals and needs: A Canadian survey 
Designing an effective training program requires information regarding the needs, capability and aspirations of its users. Prompted by the low career satisfaction levels shown by critical care medicine (CCM) clinicians in a previous survey, and a lack of data regarding the career goals of CCM trainees in Canadian training programs, this survey-based study, which had an exemplary response rate of 85%, examined career expectations, and the barriers and enablers to career goals among individuals from adult and pediatric CCM programs across Canada.
For training programs to meet the needs of trainees, an understanding of their career goals and expectations is required.
Canadian critical care medicine (CCM) trainees were surveyed to understand their career goals in terms of clinical work, research, teaching, administration and management; and to identify their perceptions regarding the support they need to achieve their goals.
The online survey was sent to all trainees registered in a Canadian adult or pediatric CCM program. It documented the participants’ demographics; their career expectations; the perceived barriers and enablers to achieve their career goals; and their perceptions relating to their chances of developing a career in different areas.
A response rate of 85% (66 of 78) was obtained. The majority expected to work in an academic centre. Only approximately one-third (31%) estimated their chances of obtaining a position in CCM as >75%. The majority planned to devote 25% to 75% of their time performing clinical work and <25% in education, research or administration. The trainees perceived that there were limited employment opportunities. Networking and having specialized expertise were mentioned as being facilitators for obtaining employment. They expressed a need for more protected time, resources and mentorship for nonclinical tasks during training.
CCM trainees perceived having only limited support to help them to achieve their career goals and anticipate difficulties in obtaining successful employment. They identified several gaps that could be addressed by training programs, including more mentoring in the areas of research, education and administration.
PMCID: PMC4128527  PMID: 24724149
Career; Critical care; Education; Needs assessment; Survey; Training
3.  De novo synthesize of bile acids in pulmonary arterial hypertension lung 
Metabolomics  2014;10(6):1169-1175.
Although multiple, complex molecular studies have been done for understanding the development and progression of pulmonary hypertension (PAH), little is known about the metabolic heterogeneity of PAH. Using a combination of high-throughput liquid-and-gas-chromatography-based mass spectrometry, we found bile acid metabolites, which are normally product derivatives of the liver and gallbladder, were highly increased in the PAH lung. Microarray showed that the gene encoding cytochrome P450 7B1 (CYP7B1), an isozyme for bile acid synthesis, was highly expressed in the PAH lung compared with the control. CYP7B1 protein was found to be primarily localized on pulmonary vascular endothelial cells suggesting de novo bile acid synthesis may be involved in the development of PAH. Here, by profiling the metabolomic heterogeneity of the PAH lung, we reveal a newly discovered pathogenesis mechanism of PAH.
Electronic supplementary material
The online version of this article (doi:10.1007/s11306-014-0653-y) contains supplementary material, which is available to authorized users.
PMCID: PMC4213391  PMID: 25374487
Bile acid pathway; Pulmonary arterial hypertension; Lung
4.  Metabolomic Heterogeneity of Pulmonary Arterial Hypertension 
PLoS ONE  2014;9(2):e88727.
Although multiple gene and protein expression have been extensively profiled in human pulmonary arterial hypertension (PAH), the mechanism for the development and progression of pulmonary hypertension remains elusive. Analysis of the global metabolomic heterogeneity within the pulmonary vascular system leads to a better understanding of disease progression. Using a combination of high-throughput liquid-and-gas-chromatography-based mass spectrometry, we showed unbiased metabolomic profiles of disrupted glycolysis, increased TCA cycle, and fatty acid metabolites with altered oxidation pathways in the human PAH lung. The results suggest that PAH has specific metabolic pathways contributing to increased ATP synthesis for the vascular remodeling process in severe pulmonary hypertension. These identified metabolites may serve as potential biomarkers for the diagnosis of PAH. By profiling metabolomic alterations of the PAH lung, we reveal new pathogenic mechanisms of PAH, opening an avenue of exploration for therapeutics that target metabolic pathway alterations in the progression of PAH.
PMCID: PMC3923046  PMID: 24533144
6.  Cardiac ischemia in patients with septic shock randomized to vasopressin or norepinephrine 
Critical Care  2013;17(3):R117.
Cardiac troponins are sensitive and specific biomarkers of myocardial necrosis. We evaluated troponin, CK, and ECG abnormalities in patients with septic shock and compared the effect of vasopressin (VP) versus norepinephrine (NE) on troponin, CK, and ECGs.
This was a prospective substudy of a randomized trial. Adults with septic shock randomly received, blinded, a low-dose infusion of VP (0.01 to 0.03 U/min) or NE (5 to 15 μg/min) in addition to open-label vasopressors, titrated to maintain a mean blood pressure of 65 to 75 mm Hg. Troponin I/T, CK, and CK-MB were measured, and 12-lead ECGs were recorded before study drug, and 6 hours, 2 days, and 4 days after study-drug initiation. Two physician readers, blinded to patient data and drug, independently interpreted ECGs.
We enrolled 121 patients (median age, 63.9 years (interquartile range (IQR), 51.1 to 75.3), mean APACHE II 28.6 (SD 7.7)): 65 in the VP group and 56 in the NE group. At the four time points, 26%, 36%, 32%, and 21% of patients had troponin elevations, respectively. Baseline characteristics and outcomes were similar between patients with positive versus negative troponin levels. Troponin and CK levels and rates of ischemic ECG changes were similar in the VP and the NE groups. In multivariable analysis, only APACHE II was associated with 28-day mortality (OR, 1.07; 95% CI, 1.01 to 1.14; P = 0.033).
Troponin elevation is common in adults with septic shock. We observed no significant differences in troponin, CK, and ECGs in patients treated with vasopressin and norepinephrine. Troponin elevation was not an independent predictor of mortality.
Trial registration ISRCTN94845869
PMCID: PMC4057204  PMID: 23786655
Septic shock; myocardial ischemia; vasopressin; norepinephrine; troponin; electrocardiogram
7.  Safety of Cell Therapy with Mesenchymal Stromal Cells (SafeCell): A Systematic Review and Meta-Analysis of Clinical Trials 
PLoS ONE  2012;7(10):e47559.
Mesenchymal stromal cells (MSCs, “adult stem cells”) have been widely used experimentally in a variety of clinical contexts. There is interest in using these cells in critical illness, however, the safety profile of these cells is not well known. We thus conducted a systematic review of clinical trials that examined the use MSCs to evaluate their safety.
Methods and Findings
MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials (to June 2011), were searched. Prospective clinical trials that used intravascular delivery of MSCs (intravenously or intra-arterially) in adult populations or mixed adult and pediatric populations were identified. Studies using differentiated MSCs or additional cell types were excluded. The primary outcome adverse events were grouped according to immediate events (acute infusional toxicity, fever), organ system complications, infection, and longer term adverse events (death, malignancy). 2347 citations were reviewed and 36 studies met inclusion criteria. A total of 1012 participants with clinical conditions of ischemic stroke, Crohn's disease, cardiomyopathy, myocardial infarction, graft versus host disease, and healthy volunteers were included. Eight studies were randomized control trials (RCTs) and enrolled 321 participants. Meta-analysis of the RCTs did not detect an association between acute infusional toxicity, organ system complications, infection, death or malignancy. There was a significant association between MSCs and transient fever.
Based on the current clinical trials, MSC therapy appears safe. However, further larger scale controlled clinical trials with rigorous reporting of adverse events are required to further define the safety profile of MSCs.
PMCID: PMC3485008  PMID: 23133515
8.  Diagnostic evaluation and management of chronic thromboembolic pulmonary hypertension: A clinical practice guideline 
Pulmonary embolism is a common condition. Some patients subsequently develop chronic thromboembolic pulmonary hypertension (CTEPH). Many care gaps exist in the diagnosis and management of CTEPH patients including lack of awareness, incomplete diagnostic assessment, and inconsistent use of surgical and medical therapies.
A representative interdisciplinary panel of medical experts undertook a formal clinical practice guideline development process. A total of 20 key clinical issues were defined according to the patient population, intervention, comparator, outcome (PICO) approach. The panel performed an evidence-based, systematic, literature review, assessed and graded the relevant evidence, and made 26 recommendations.
Asymptomatic patients postpulmonary embolism should not be screened for CTEPH. In patients with pulmonary hypertension, the possibility of CTEPH should be routinely evaluated with initial ventilation/ perfusion lung scanning, not computed tomography angiography. Pulmonary endarterectomy surgery is the treatment of choice in patients with surgically accessible CTEPH, and may also be effective in CTEPH patients with disease in more ‘distal’ pulmonary arteries. The anatomical extent of CTEPH for surgical pulmonary endarterectomy is best assessed by contrast pulmonary angiography, although positive computed tomography angiography may be acceptable. Novel medications indicated for the treatment of pulmonary hypertension may be effective for selected CTEPH patients.
The present guideline requires formal dissemination to relevant target user groups, the development of tools for implementation into routine clinical practice and formal evaluation of the impact of the guideline on the quality of care of CTEPH patients. Moreover, the guideline will be updated periodically to reflect new evidence or clinical approaches.
PMCID: PMC3006154  PMID: 21165353
Chronic thromboembolic pulmonary hypertension; Clinical practice guideline; Pulmonary endarterectomy; Pulmonary hypertension; Thromboembolism
9.  Feasibility of Internet-Based Health-Related Quality of Life Data Collection in a Large Patient Cohort 
Patient registries are commonly used to track survival and medical outcomes in large cohorts. However, large-scale collection of health-related quality of life (HRQOL) data is more challenging because such data must be collected directly from patients. Internet-based HRQOL questionnaires are a potential solution, allowing home data collection with immediate storage in a central database.
Our objectives were to investigate the sociodemographic predictors of Internet use and willingness to convey HRQOL information over the Internet in a Canadian tertiary care patient population and to determine whether Internet use patterns of tertiary care patients differ from those of the general Canadian population. Additionally, we sought to identify the success of home completion of Internet-based HRQOL questionnaires, as well as factors hindering home completion.
We surveyed 644 patients at the Toronto General and St. Michael’s Hospitals from November 2003 through July 2006 within a prospective, longitudinal cohort study of HRQOL in patients with lung disease or lung transplants. Using multiple logistic regression, we assessed patient age, gender, rurality, marital status, and employment or education status as potential sociodemographic predictors of having an Internet-accessible home computer, using email at least weekly, and willingness to complete a quality of life questionnaire over the Internet. Patients electing to complete questionnaires over the Internet were followed from September 2005 through March 2008 to assess completion of HRQOL questionnaires from home, identify barriers for noncompletion, and determine sociodemographic predictors for home completion.
Of the 644 patients, the median age was 51 years, with a similar number of males and females. Most were urban Ontario residents, were unemployed, and were married or in a common-law relationship. Having an Internet-accessible home computer was reported by 79.7% (513/644) of patients and use of email at least weekly by 66.5% (414/623) of patients. A majority of patients (57.1% 368/644) were willing to complete HRQOL questionnaires over the Internet via an emailed link. Of the participating 644 patients, 368 elected to complete future questionnaires from home and, as part of a gradual roll-out of the home HRQOL questionnaire, 211 were sent emails inviting them to do so. Of the invited patients, 78% (165/211) completed at least one questionnaire from home. The most common reason for noncompletion was a lack of or an inability to find time to complete the questionnaire. No statistically significant sociodemographic predictors of Internet use were associated with completion or noncompletion of questionnaires from home.
Home, Internet-based HRQOL assessment is feasible in tertiary care patient populations with a high predicted rate of Internet usage based on sociodemographic parameters. A large minority of patients were unwilling or unable to take part in home HRQOL assessments indicating that alternative methods of data collection are still required. However, the majority of patients electing to complete home HRQOL assessments went on to do so over the Internet.
PMCID: PMC2956333  PMID: 20719740
Quality of life; cohort studies; Internet; feasibility studies; lung diseases
10.  Prophylactic anticoagulation to prevent venous thromboembolism in traumatic intracranial hemorrhage: a decision analysis 
Critical Care  2010;14(2):R72.
Patients with intracranial hemorrhage due to traumatic brain injury are at high risk of developing venous thromboembolism including deep vein thrombosis (DVT) and pulmonary embolism (PE). Thus, there is a trade-off between the risks of progression of intracranial hemorrhage (ICH) versus reduction of DVT/PE with the use of prophylactic anticoagulation. Using decision analysis modeling techniques, we developed a model for examining this trade-off for trauma patients with documented ICH.
The decision node involved the choice to administer or to withhold low molecular weight heparin (LMWH) anticoagulation prophylaxis at 24 hours. Advantages of withholding therapy were decreased risk of ICH progression (death, disabling neurologic deficit, non-disabling neurologic deficit), and decreased risk of systemic bleeding complications (death, massive bleed). The associated disadvantage was greater risk of developing DVT/PE or death. Probabilities for each outcome were derived from natural history studies and randomized controlled trials when available. Utilities were obtained from accepted databases and previous studies.
The expected value associated with withholding anticoagulation prophylaxis was similar (0.90) to that associated with the LMWH strategy (0.89). Only two threshold values were encountered in one-way sensitivity analyses. If the effectiveness of LMWH at preventing DVT exceeded 80% (range from literature 33% to 82%) our model favoured this therapy. Similarly, our model favoured use of LMWH if this therapy increased the risk of ICH progression by no more than 5% above the baseline risk.
Our model showed no clear advantage to providing or withholding anticoagulant prophylaxis for DVT/PE prevention at 24 hours after traumatic brain injury associated with ICH. Therefore randomized controlled trials are justifiable and needed to guide clinicians.
PMCID: PMC2887195  PMID: 20406444
11.  Adaptation of the Cambridge Pulmonary Hypertension Outcome Review (CAMPHOR) into French-Canadian and English-Canadian 
The Cambridge Pulmonary Hypertension Outcome Review (CAMPHOR) is the first disease-specific instrument for assessing patient-reported symptoms, functioning and quality of life (QoL) in pulmonary arterial hypertension (PAH).
To create and validate French-Canadian (FC) and English-Canadian (EC) language versions of the CAMPHOR.
A translation panel (for the FC version) and lay panels (for both versions) were convened to adapt the questionnaires (dual-panel methodology). Subsequently, these new questionnaires were field-tested in 15 FC PAH and 15 EC PAH patients. Finally, in a postal validation study, the new language versions of the CAMPHOR underwent psychometric evaluation in 41 FC and 52 EC PAH patients to test for reliability and validity.
The FC and EC field-test interview participants found the questionnaires relevant, comprehensible and easy to complete. Psychometric analyses showed that the FC and EC adaptations were successful. High test-retest coefficients for the scales after controlling for change in respondent’s QoL (FC: 0.92 to 0.96; EC: 0.85 to 0.99) indicated a high degree of reliability. The FC and EC CAMPHOR scales had good internal consistency (Cronbach’s alpha coefficients 0.90 to 0.92 and 0.88 to 0.92, respectively). Predicted correlations with the Nottingham Health Profile provided evidence of the construct validity of the FC and EC scales. The FC and EC adaptations also showed known groups validity.
The FC and EC adaptations of the CAMPHOR have been shown to be reliable and valid for measures of health-related QoL and QoL in PAH, and thus can be recommended for use in clinical studies and routine practice in PAH.
PMCID: PMC2677839  PMID: 18354747
Adaptation; Health status; Pulmonary arterial hypertension; Quality of life; Questionnaire; Validity
12.  Venous thromboembolism and bleeding in critically ill patients with severe renal insufficiency receiving dalteparin thromboprophylaxis: prevalence, incidence and risk factors 
Critical Care  2008;12(2):R32.
Critically ill patients with renal insufficiency are predisposed to both deep vein thrombosis (DVT) and bleeding. The objective of the present study was to evaluate the prevalence, incidence and predictors of DVT and the incidence of bleeding in intensive care unit (ICU) patients with estimated creatinine clearance <30 ml/min.
In a multicenter, open-label, prospective cohort study of critically ill patients with severe acute or chronic renal insufficiency or dialysis receiving subcutaneous dalteparin 5,000 IU once daily, we estimated the prevalence of proximal DVT by screening compression venous ultrasound of the lower limbs within 48 hours of ICU admission. DVT incidence was assessed on twice-weekly ultrasound testing. We estimated the incidence of major and minor bleeding by daily clinical assessments. We used Cox proportional hazards regression to identify independent predictors of both DVT and major bleeding.
Of 156 patients with a mean (standard deviation) creatinine clearance of 18.9 (6.5) ml/min, 18 had DVT or pulmonary embolism within 48 hours of ICU admission, died or were discharged before ultrasound testing – leaving 138 evaluable patients who received at least one dose of dalteparin. The median duration of dalteparin administration was 7 days (interquartile range, 4 to 12 days). DVT developed in seven patients (5.1%; 95% confidence interval, 2.5 to 10.1). The only independent risk factor for DVT was an elevated baseline Acute Physiology and Chronic Health Evaluation II score (hazard ratio for 10-point increase, 2.25; 95% confidence interval, 1.03 to 4.91). Major bleeding developed in 10 patients (7.2%; 95% confidence interval, 4.0 to 12.8), all with trough anti-activated factor X levels ≤ 0.18 IU/ml. Independent risk factors for major bleeding were aspirin use (hazard ratio, 6.30; 95% confidence interval, 1.35 to 29.4) and a high International Normalized Ratio (hazard ratio for 0.5-unit increase, 1.68; 95% confidence interval, 1.07 to 2.66).
In ICU patients with renal insufficiency, the incidence of DVT and major bleeding are considerable but appear related to patient comorbidities rather than to an inadequate or excessive anticoagulant from thromboprophylaxis with dalteparin.
Clinical Trial Registration
Number NCT00138099.
PMCID: PMC2447552  PMID: 18315876
13.  Eisenmenger syndrome and atrial septal defect: Nature or nurture? 
The Canadian Journal of Cardiology  2006;22(13):1133-1136.
It has long been debated whether patients with atrial septal defect (ASD) Eisenmenger syndrome have idiopathic pulmonary arterial hypertension with an incidental ASD or severe pulmonary hypertension on the basis of their ASD shunt magnitude alone.
It was hypothesized that if ASD Eisenmenger patients had idiopathic pulmonary arterial hypertension with an incidental ASD, a mutation in the bone morphogenetic protein receptor-2 (BMPR2) would be found in some of these patients.
All adult patients with ASD Eisenmenger syndrome were identified from the databases of two adult congenital cardiac units, and were matched to a control group with similar types of ASDs and no pulmonary hypertension. Gene coding for BMPR2 was examined for mutation using denaturing high-performance liquid chromatography of the entire coding sequence.
Eighteen adult patients with ASD Eisenmenger syndrome and 18 control patients were identified. ASD Eisenmenger patients had significantly larger ASDs than the control patients (3.7±1.2 cm versus 1.9±0.7 cm, P<0.01). A mutation in BMPR2 was not detected in either group.
ASD Eisenmenger syndrome may occur without BMPR2 mutation. Whether shunt magnitude alone or in combination with yet another genetic mutation is responsible for the development of pulmonary hypertension in these patients remains to be determined.
PMCID: PMC2569052  PMID: 17102831
Atrial septal defect; Genetics; Pulmonary hypertension
14.  An open-label, multicentre pilot study of bosentan in pulmonary arterial hypertension related to congenital heart disease 
Bosentan has been shown to be a safe and efficacious treatment for idiopathic pulmonary arterial hypertension (PAH) and PAH associated with connective tissue disease. However, there are limited studies examining the benefits of bosentan in PAH associated with congenital heart disease (CHD).
The aim of the present pilot study was to explore the safety and efficacy of bosentan in patients with PAH associated with CHD.
In the present study, 11 patients with PAH associated with CHD were enrolled to receive bosentan for a minimum of 16 weeks (62.5 mg twice a day for four weeks; thereafter 125 mg twice a day). Safety was assessed by monitoring adverse events, oxygen saturation, systemic blood pressure, pulse, complete blood count and liver function tests. Efficacy was assessed by the World Health Organization functional class, 6 min walk test (6-MWT), modified Borg dyspnea index, echocardiography and the 36-item short form health survey.
Ten patients completed the 16-week treatment period (one patient withdrew). Bosentan was not associated with a deterioration in resting oxygen saturation (83.0±4.6% at week 16 versus 81.9±6.1% at baseline; P=0.402), or a deterioration in post-6-MWT oxygen saturation (70.1±10.9% at week 16 versus 68.7±15.1% at baseline; P=0.747). Two patients experienced three serious adverse events. The distance walked in 6 min improved significantly by 28 m (P=0.005) at week 16 compared with baseline, and the modified Borg dyspnea index also improved at week 16 compared with baseline (P=0.050). The World Health Organization functional class improved from class III to class II for five of 10 patients (50%). Patients’ self-rated quality of life (36-item short form health survey) demonstrated a non-significant improvement in each of the eight domains. Obtaining reliable echocardiographic measurements was difficult. Most echocardiographic parameters were only measurable on few patients, and none were measured on all patients, questioning the usefulness of echocardiography as a measuring tool for patients with complex CHD.
Bosentan was not associated with worsening of resting oxygen saturation or exercise systemic oxygen saturation, suggesting its potential as a safe treatment option for patients with PAH associated with CHD. Improved 6-MWT and the modified Borg dyspnea index also suggested the possibility of bosentan as an efficacious treatment option for these patients. The results of the present study provide evidence for the need and feasibility of a large randomized, placebo-controlled clinical trial.
PMCID: PMC2683328  PMID: 17149459
Congenital heart disease; Endothelin; Hypoxia; Pulmonary hypertension
15.  Effect of nitric oxide on oxygenation and mortality in acute lung injury: systematic review and meta-analysis 
BMJ : British Medical Journal  2007;334(7597):779.
Objective To review the literature on the use of inhaled nitric oxide to treat acute lung injury/acute respiratory distress syndrome (ALI/ARDS) and to summarise the effects of nitric oxide, compared with placebo or usual care without nitric oxide, in adults and children with ALI or ARDS.
Design Systematic review and meta-analysis.
Data sources Medline, CINAHL, Embase, and CENTRAL (to October 2006), proceedings from four conferences, and additional information from authors of 10 trials.
Review methods Two reviewers independently selected parallel group randomised controlled trials comparing nitric oxide with control and extracted data related to study methods, clinical and physiological outcomes, and adverse events.
Main outcome measures Mortality, duration of ventilation, oxygenation, pulmonary arterial pressure, adverse events.
Results 12 trials randomly assigning 1237 patients met inclusion criteria. Overall methodological quality was good. Using random effects models, we found no significant effect of nitric oxide on hospital mortality (risk ratio 1.10, 95% confidence interval 0.94 to 1.30), duration of ventilation, or ventilator-free days. On day one of treatment, nitric oxide increased the ratio of partial pressure of oxygen to fraction of inspired oxygen (PaO2/FiO2 ratio) (13%, 4% to 23%) and decreased the oxygenation index (14%, 2% to 25%). Some evidence suggested that improvements in oxygenation persisted until day four. There was no effect on mean pulmonary arterial pressure. Patients receiving nitric oxide had an increased risk of developing renal dysfunction (1.50, 1.11 to 2.02).
Conclusions Nitric oxide is associated with limited improvement in oxygenation in patients with ALI or ARDS but confers no mortality benefit and may cause harm. We do not recommend its routine use in these severely ill patients.
PMCID: PMC1852043  PMID: 17383982
17.  Critical care procedure logging using handheld computers 
Critical Care  2004;8(5):R336-R342.
We conducted this study to evaluate the feasibility of implementing an internet-linked handheld computer procedure logging system in a critical care training program.
Subspecialty trainees in the Interdepartmental Division of Critical Care at the University of Toronto received and were trained in the use of Palm handheld computers loaded with a customized program for logging critical care procedures. The procedures were entered into the handheld device using checkboxes and drop-down lists, and data were uploaded to a central database via the internet. To evaluate the feasibility of this system, we tracked the utilization of this data collection system. Benefits and disadvantages were assessed through surveys.
All 11 trainees successfully uploaded data to the central database, but only six (55%) continued to upload data on a regular basis. The most common reason cited for not using the system pertained to initial technical problems with data uploading. From 1 July 2002 to 30 June 2003, a total of 914 procedures were logged. Significant variability was noted in the number of procedures logged by individual trainees (range 13–242). The database generated by regular users provided potentially useful information to the training program director regarding the scope and location of procedural training among the different rotations and hospitals.
A handheld computer procedure logging system can be effectively used in a critical care training program. However, user acceptance was not uniform, and continued training and support are required to increase user acceptance. Such a procedure database may provide valuable information that may be used to optimize trainees' educational experience and to document clinical training experience for licensing and accreditation.
PMCID: PMC1065023  PMID: 15469577
critical care; handheld computers; internet; procedure logging; training program
18.  Clinically important deep vein thrombosis in the intensive care unit: a survey of intensivists 
Critical Care  2004;8(3):R145-R152.
Outside the intensive care unit (ICU), clinically important deep vein thrombosis (DVT) is usually defined as a symptomatic event that leads to objective radiologic confirmation and subsequent treatment. The objective of the present survey is to identify the patient factors and radiologic features of lower limb DVT that intensivists consider more or less likely to make a DVT clinically important in ICU patients.
Our definition of clinically important DVT was a DVT likely to result in short-term or long-term morbidity or mortality if left untreated, as opposed to a DVT that is unlikely to have important consequences. We asked respondents to indicate the likelihood that patient factors and ultrasonographic features make a DVT clinically important using a five-point scale (from 1 = much less likely to 5 = much more likely).
Of the 71 Canadian intensivists who responded, 70 (99%) rated three patient factors as most likely to make a DVT clinically important: clinical suspicion of pulmonary embolism (mean score 4.6), acute or chronic cardiopulmonary morbidity that might limit a patient's ability to tolerate pulmonary embolism (score 4.5), and leg symptoms (score 4.2). Of the ultrasound features, proximal (score 4.7), large (score 4.2), and totally occlusive (score 3.9) thrombi were considered the three most important.
When labeling a DVT as clinically important, intensivists rely on different patient specific factors and thrombus characteristics than are used to assess the clinical importance of DVT outside the ICU. The clinical importance of DVT is influenced by unique factors such as cardiopulmonary reserve among mechanically ventilated patients.
PMCID: PMC468908  PMID: 15153243
deep venous thrombosis; pulmonary embolism; ultrasound
20.  Science Review: Vasopressin and the cardiovascular system part 2 – clinical physiology 
Critical Care  2003;8(1):15-23.
Vasopressin is emerging as a rational therapy for vasodilatory shock states. In part 1 of the review we discussed the structure and function of the various vasopressin receptors. In part 2 we discuss vascular smooth muscle contraction pathways with an emphasis on the effects of vasopressin on ATP-sensitive K+ channels, nitric oxide pathways, and interaction with adrenergic agents. We explore the complex and contradictory studies of vasopressin on cardiac inotropy and coronary vascular tone. Finally, we summarize the clinical studies of vasopressin in shock states, which to date have been relatively small and have focused on physiologic outcomes. Because of potential adverse effects of vasopressin, clinical use of vasopressin in vasodilatory shock should await a randomized controlled trial of the effect of vasopressin's effect on outcomes such as organ failure and mortality.
PMCID: PMC420051  PMID: 14975041
adrenergic agents; antidiurectic hormone; cardiac inotropy; hypotension; nitric oxide; oxytocin; physiology; potassium channels; receptors; septic shock; smooth muscle; vascular; vasoconstriction; vasodilation; vasopressin
21.  Science Review: Vasopressin and the cardiovascular system part 1 – receptor physiology 
Critical Care  2003;7(6):427-434.
Vasopressin is emerging as a rational therapy for vasodilatory shock states. Unlike other vasoconstrictor agents, vasopressin also has vasodilatory properties. The goal of the present review is to explore the vascular actions of vasopressin. In part 1 of the review we discuss structure, signaling pathways, and tissue distributions of the classic vasopressin receptors, namely V1 vascular, V2 renal, V3 pituitary and oxytocin receptors, and the P2 class of purinoreceptors. Knowledge of the function and distribution of vasopressin receptors is key to understanding the seemingly contradictory actions of vasopressin on the vascular system. In part 2 of the review we discuss the effects of vasopressin on vascular smooth muscle and the heart, and we summarize clinical studies of vasopressin in shock states.
PMCID: PMC374366  PMID: 14624682
adrenergic agents; antidiurectic hormone; cardiac inotropy; hypotension; nitric oxide; oxytocin; physiology; potassium channels; receptors; septic shock; smooth muscle; vasoconstriction; vascular; vasodilation; vasopressin

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